C-4

Composition C4, is a plastic explosive developed in the 1960s as an improvement to a pre-existing plastic explosive called Nobel 808. C-4 is a combination of explosive, a plastic binding agent, a plasticizer, and a marking chemical added to ease detection.

Like all plastic explosives, C-4 is extremely stable. Called an insensitive explosive, C-4 is very difficult to trigger by accident. Impact and fire are separately not enough to detonate C-4, but the combination of the two can create the necessary circumstances for detonation. Fire will cause C-4 to burn with very high heat, even underwater, and was often used by U.S. troops in Vietnam to cook food. C-4 is 1.34 times more explosive than TNT.

Uses in the series

Essam Tasir and Sayid were supposed to carry out a suicide bombing mission with a truck full of the C-4 explosive. Essam killed himself before they could carry out the plan. ("The Greater Good")

C-4 was the explosive used in the self-destruct system built into the Flame communications station. Several blocks of C-4 were strategically placed at the join between the subsurface section wall and the ceiling. The size of the blocks indicated a standard two-kilogram demolitions charge, common to military units. A series of these blocks would be more than sufficient to destroy the station. ("Enter 77")

Locke removed at least one of the C-4 blocks from the Flame station before it was destroyed. Rousseau suggested using this explosive to destroy one of the pylons in the sonic barrier, but the plan was deemed too dangerous. ("Par Avion")

Returning to the Island on the Kahana, Michael was sent a toolbox filled with explosives. He took the toolbox down to the engine room and prepared to activate the bomb. Libby briefly appeared to him and told him not to do it, but she disappeared and Michael shook off the apparent hallucination. He punched in a detonation count, but at the end of a short countdown, rather than detonating, the bomb popped up a flag reading "NOT YET". ("Meet Kevin Johnson")